package com.aoxun.android.commons.util;
/**
 * Created by Onelong on 2017/11/20.
 */
import android.content.Context;
import android.content.SharedPreferences;
import android.provider.Settings.Secure;
import android.telephony.TelephonyManager;
import android.text.TextUtils;

import java.util.UUID;

public class DeviceUuidUtil {
	protected static final String PREFS_FILE = "device_id.xml";
	protected static final String PREFS_DEVICE_ID = "device_id";
	protected static UUID uuid;

	public DeviceUuidUtil(Context context) {
		if (uuid == null) {
			synchronized (DeviceUuidUtil.class) {
				if (uuid == null) {
					final SharedPreferences prefs = context
							.getSharedPreferences(PREFS_FILE, 0);
					final String id = prefs.getString(PREFS_DEVICE_ID, null);
					if (id != null) {
						// Use the ids previously computed and stored in the
						// prefs file
						uuid = UUID.fromString(id);
					} else {
						final String androidId = Secure
								.getString(context.getContentResolver(),
										Secure.ANDROID_ID);
						// Use the Android ID unless it's broken, in which case
						// fallback on deviceId,
						// unless it's not available, then fallback on a random
						// number which we store
						// to a prefs file
						try {
							if (!TextUtils.isEmpty(androidId)
									&& !"9774d56d682e549c".equals(androidId)) {
								uuid = UUID.nameUUIDFromBytes(androidId
										.getBytes("utf8"));
							} else {
								final String deviceId = ((TelephonyManager) context
										.getSystemService(Context.TELEPHONY_SERVICE))
										.getDeviceId();
								uuid = deviceId != null ? UUID
										.nameUUIDFromBytes(deviceId
												.getBytes("utf8")) : UUID
										.randomUUID();
							}
						} catch (Exception e) {
							uuid= UUID
								.randomUUID();
						}
						// Write the value out to the prefs file
						prefs.edit()
								.putString(PREFS_DEVICE_ID, uuid.toString())
								.commit();
					}
				}
			}
		}
	}

	/**
	 * Returns a unique UUID for the current android device. As with all UUIDs,
	 * this unique ID is "very highly likely" to be unique across all Android
	 * devices. Much more so than ANDROID_ID is.
	 * 
	 * The UUID is generated by using ANDROID_ID as the base key if appropriate,
	 * falling back on TelephonyManager.getDeviceID() if ANDROID_ID is known to
	 * be incorrect, and finally falling back on a random UUID that's persisted
	 * to SharedPreferences if getDeviceID() does not return a usable value.
	 * 
	 * In some rare circumstances, this ID may change. In particular, if the
	 * device is factory reset a new device ID may be generated. In addition, if
	 * a user upgrades their phone from certain buggy implementations of Android
	 * 2.2 to a newer, non-buggy version of Android, the device ID may change.
	 * Or, if a user uninstalls your app on a device that has neither a proper
	 * Android ID nor a Device ID, this ID may change on reinstallation.
	 * 
	 * Note that if the code falls back on using TelephonyManager.getDeviceId(),
	 * the resulting ID will NOT change after a factory reset. Something to be
	 * aware of.
	 * 
	 * Works around a bug in Android 2.2 for many devices when using ANDROID_ID
	 * directly.
	 * 
	 * @see http://code.google.com/p/android/issues/detail?id=10603
	 * 
	 * @return a UUID that may be used to uniquely identify your device for most
	 *         purposes.
	 */
	public UUID getDeviceUuid() {
		return uuid;
	}
}